This is one of those things that has never been fully interpreted by the Supreme Court and is only vaguely referred to in the Constitution in what is referred to as the “Appointments Clause”. The text of that clause, which is Article II, Section 2, states that the President “shall nominate, and, by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States, whose Appointments are not herein otherwise provided for, and which shall be established by Law: but the Congress may by Law vest the Appointment of such inferior Officers, as they think proper, in the President alone, in the Courts of Law, or in the Heads of Departments.”
What those “Departments” actually were wasn’t made specifically clear, but the common interpretation (and the one that makes the most sense) of those “Departments” is of the agencies of the federal government that exercise the power of the Executive Branch. What the “Heads of Department” were is less clear and has never been defined by the Supreme Court, but it has been taken to mean that there are principal “Officers” and “inferior Officers” within those Departments — the principal “Officers” require Senate confirmation while the “inferior Officers” do not unless Congress specifically mandates it. The principal “Officers” are not just the Secretaries of each Cabinet-level Department and Senate confirmation isn’t limited to agencies considered Cabinet-level Departments. There are nearly 1,500 positions in the federal government which require Senate confirmation after Presidential appointment.
The formation of these Departments and the reason for Cabinet Secretaries is basically, to put it really simply, because there’s a lot of damn work to do. The President is vested with all of this Executive power, but the President is just one person. The Legislative Branch has hundreds of members in elected positions and even the Supreme Court has nine members, and that’s not even counting all of the lower courts in the Judicial Branch. To use the Department of State/Secretary of State as an example since that’s the one you mentioned, the Constitution gives the President the responsibility for our country’s foreign relations. Even during George Washington’s Presidency when the size of the country and the government was small, it was obvious that the President couldn’t single-handedly administer foreign policy, manage the financial system and law enforcement/legal apparatus, and be Commander-in-Chief of the military. The President needed help, so Departments were formed and people were put in charge of those Departments.
The State Department was a no-brainer, and during the Washington Administration, it was followed by a Treasury Department (finance), War Department (defense), and Attorney General (justice). There was actually no Department of Justice until 1870. Prior to that, the Attorney General was a Presidential appointee who was responsible for prosecuting cases before the Supreme Court and as the Executive Branch’s legal authority who could give opinions and advice on the law. When it comes to the technical process of establishing a federal Department, the President usually appoints an official responsible for a specific role or advocates for the establishment of such a role and Congress passes a law creating the Department needed to support that Presidential appointee. As the government and country has grown and different technologies and industries have sprouted, new Departments have been added or have been turned into something else.
The establishment of a Department of State was obviously the most important Department to the leaders when the Presidency went into effect because of its role in supporting the President in foreign relations at a time where even some of our more cosmopolitan leaders were regarded (often quite accurately) as somewhat provincial. Foreign policy was a big concern because the United States was still recovering from a Revolutionary War which resulted in independence but required everything Americans had as well as the assistance of foreign allies (or foreign countries who were at least enemies of England). Strengthening those ties, along with building new ones, was an absolute necessity for defensive and economic reasons — for survival, basically. That’s why the Department of State was the first to be created shortly after Washington was inaugurated. At first, it was actually called the “Department of Foreign Affairs”, but Congress changed the name to the “Department of State” right before Thomas Jefferson was appointed as the first Secretary of State a couple of months later.
More Cabinet-level Departments — along with sub Cabinet-level agencies, many of which also have principal officers who require Senate confirmation following Presidential appointment — have been established throughout our history, but the Secretary of State has largely remained the most important position in the Cabinet. Like the Chief Justice, the Secretary of State is seen as first-among-equals, and was such an important and influential position that the Secretary is first in the order of precedence of members of the Cabinet and was second in line to the Presidency from 1886 until 1947. Early Secretaries of State were so influential that the position seemed to be a stepping stone to the Presidency during the first 50 years of the job’s existence with four of the first six Presidents (Thomas Jefferson, James Madison, James Monroe, and John Quincy Adams) being former Secretaries of State. Three Secretaries of State (Madison, Monroe, and J.Q. Adams) were elected to the Presidency directly from the State Department. However, only two former Secretaries of State have been elected President since 1825 — Martin Van Buren, Secretary of State under President Jackson (1829-1831) and elected President in 1836, and James Buchanan, Secretary of State under President Polk (1845-1849) and elected President in 1856 — so, if she is successful in 2016, Hillary Clinton will be the first former Secretary of State elected President in 160 years. And it won’t be for a lack of trying — former Secretaries of State who were nominated by a major party but lost a Presidential election include Henry Clay (lost three Presidential election), Daniel Webster (lost two Presidential elections), Lewis Cass, and James G. Blaine. Several others unsuccessfully sought their party’s nomination and lost or settled for the State Department after losing a Presidential election first (including William Jennings Bryan, who lost three Presidential elections).
This is way more information than jrobertxiii asked for, but I hope it answered some of your questions.
At the beginning of the 19th Century, being Secretary of State was almost a guarantee that you’d be elected President. Five of the first eight Presidents had served as Secretary of State, including three (James Madison, James Monroe, and John Quincy Adams) who went directly to the White House from serving two terms as Secretary of State. But it’s been nearly 160 years since the last Secretary of State — James Buchanan, who ran President Polk’s State Department from 1845 to 1849 — was elected President.
I think it’s more difficult now for a couple of reasons. First of all, Secretaries of State aren’t nearly as powerful now. The Vice Presidency is a far more influential position today than it was in the 18th, 19th, and first half of the 20th Century, the White House Chief of Staff handles the Administration’s COO-type responsibilities that many Secretaries previously took on, and as other Cabinet posts have increased their profile within the Executive Department it has diminished the power of the Secretary of State, especially when there are turf wars like the feud between Colin Powell and Donald Rumsfeld. The Secretary of State used to be a Foreign Minister-type position that was basically just short of being equivalent to a Prime Minister; in many ways, the Secretary of State used to be (unofficially) the first-among-equals within the Cabinet. That changed a bit early in the 20th Century, but especially in the latter part of the last century. Basically since Nixon’s Presidency, American foreign policy is almost fully run by the White House through the National Security Staff (formerly known as the National Security Council). The Secretary of State is a member of the National Security Staff and has a role in formulating that policy, of course, but they are more like Super Ambassadors who go where the President sends them and relays messages. They have always been the top American diplomat, but the job now is much more political, domestically and internationally, than administrative.
Another reason why you don’t see more Secretaries of State running for President directly from the State Department is purely political. If a President serves a single term, a Secretary of State isn’t going to be an ideal candidate because they’d have to challenge their boss. If a President serves two terms, there is usually voter fatigue when it comes to the President and his Cabinet. After two terms, the opposition party will have been sharpening their knives and getting ready for the Presidential election. A Secretary of State who has either served two terms in office or wants to run for President directly from the State Department after one term in the Cabinet is an easy target. All Presidents eventually become lame ducks and if someone is serving in their Cabinet as the President’s popularity starts to take a dive, they’ll usually be painted with that same brush. It’s easy to run against them — whether you’re from the other party or challenging them in the primary.
Hillary Clinton would have a more difficult race in front of her if she were serving as Secretary of State in Obama’s Cabinet right now. It would be easier to connect her with an unpopular President who is rapidly heading towards lame duck status if she were currently in the Cabinet. Since she left after the first term, on her own terms, after Obama had been re-elected, she basically left at the perfect time — it’s like when an athlete retires after winning a championship. If you go out on top, you control your destiny and shore up your legacy. So, that’s why no Secretaries of State have been elected President since Buchanan in 1856 and few have even won their party’s nomination. But, if things play out the way I think they will, Hillary will end that drought in 2016.
Diplomacy in the [George W.] Bush Administration is, ‘Alright, you fuckers, do what we say.’”
Richard Armitage, George W. Bush’s Deputy Secretary of State
I think Senator Kerry is an excellent choice. He has a wealth of experience in foreign relations due to his lengthy service on that committee in the Senate, is well-known around the world, and has built personal relationships with many international leaders that will serve him and the President well once he takes over at State. I think that Susan Rice got a raw deal over the Benghazi attacks and was unfairly made out to be the scapegoat, but I also think Kerry is a much more solid pick for Secretary of State than Rice would have been.